Abstract

Centenarians have been reported to
share particular personality traits including low neuroticism and high
extraversion and conscientiousness. Since these traits have moderate to
high heritability and are associated with various health
outcomes, personality appears linked to bio-genetic mechanisms which may
contribute to exceptional longevity. Therefore, the present study sought to
detect genetically-based personality phenotypes in a genetically homogeneous
sample of centenarians through developing and examining psychometric
properties of a brief measure of the personality of centenarians, the
Personality Outlook Profile Scale (POPS). The results generated two
personality characteristics/domains, Positive Attitude Towards Life (PATL:
optimism, easygoing, laughter, and introversion/outgoing) and Emotional
Expression (EE: expressing emotions openly and not bottling up emotions).
These domains demonstrated acceptable concurrent validity with two
established personality measures, the NEO-Five Factor Inventory and Life
Orientation Test-Revised. Additionally, centenarians in both groups had
lower neuroticism and higher conscientiousness than the US adult
population. Findings suggest that the POPS is a psychometrically sound
measure of personality in centenarians and capture personality aspects of
extraversion, neuroticism, and conscientiousness, as well as dispositional
optimism which may contribute to successful aging.

INTRODUCTION

Living
to be 100 years of age is still a rare event. According to the US Census
Bureau, there are approximately 53,000 centenarians in the US which remain only
.2% of the population [1]. The number of centenarians has been rapidly
increasing at a rate of 8% per year in the US [2]. Some suggest that
centenarians may carry biological markers of successful aging since by and
large they have delayed or escaped major illnesses [3]. However, less is known
regarding factors which contribute to diversity in successful aging/longevity
in centenarians [4].

Among many factors associated with
longevity, personality has been linked to health outcomes and longevity [5].
Personality refers to a stable set of cognitive,
motivational, social, and emotional traits and behavioral patterns, which is
influenced by familial history, genetic predisposition, environment, and
socio-cultural factors [6]. The NEO Personality Inventory-Revised (NEO-PI-R)
and NEO-Five Factor Inventory (NEO-FFI) are personality measures developed for
longitudinal studies of personality and aging [7] and are based on the Five
Factor Model (FFM) which represents traits including neuroticism/emotional
stability, extraversion, openness to experience, agreeableness, and
conscientiousness. Select FFM traits have been associated with favorable health
outcomes and longevity in older adults [5,8-10].

Additionally,
several studies have suggested that centenarians also share particular
personality traits. The Georgia Centenarian Study reported that centenarians have a lower level of neuroticism and higher
levels of extraversion, competence (a facet of conscientiousness), and trust (a
facet of agreeableness) than the mixed-age US population [9]. Similarly,
Japanese cognitively intact female centenarians were reported to have higher
levels of extraversion and conscientiousness than the Japanese middle-aged and
older adults [11]. Further, the Swedish Centenarian Study [12] showed that
centenarians appeared more easygoing, relaxed, capable, and efficient than the
Swedish mixed-age population.

The
personality - longevity relationship has been further explored by examining
pathways through which personality may influence health outcomes. Achieving 100
years of age seems to have a very strong genetic influence [13], and the
genetic contribution has been found to be the largest in the oldest old
population [14]. Personality may represent underlying genetic and
neurophysiological mechanisms which may directly affect health outcomes [15,16]. Additionally, certain personality traits shared by centenarians such as
low neuroticism and high extraversion and conscientiousness [9,11] may also
have strong heritable/genetic components [16]. Distel and colleagues [17] reported
that heritability estimates of FFM personality traits such as neuroticism,
conscientiousness, and extraversion were 43%, 43%, and 47% respectively,
suggesting that these traits are highly heritable. Similarly, the offspring of
centenarians have been reported to show a lower level of neuroticism and a
higher level of extraversion than the general population [18].

Second,
personality traits (e.g., neuroticism, an enduring tendency to experience
negative emotions) may affect health outcomes through mediating processes such
as emotion regulation [19]. Specifically, depression, which may be viewed as a
result of emotion dysregulation, has been reported to be a significant
predictor for negative health outcomes and mortality [20-22], and neuroticism
has been found to be an important risk factor for depression [19] and early
mortality [23]. Further, some researchers argue that prolonged negative affect (e.g., depression and anxiety) is linked to
disease susceptibility through physiological changes in SNS (sympathetic
nervous system), HPA (hypothalamic-pituitary-adrenal) axis, stress hormones,
blood pressure, metabolism, and immune function [19,23-26]. Therefore,
mediators linked to personality traits, such as chronic emotion dysregulation
may have an adverse impact on health outcomes through their effect on
physiological/biological function.

Third, personality may influence health
outcomes through affecting an individual's choice of health-related behaviors
[5,12,27]. Conscientiousness has been tied to longevity, and research
suggests that people with high conscientiousness tend to practice healthy
behaviors (e.g., engaging in physical exercise) and avoid risky health
behaviors (e.g., excessive drinking and smoking) [28-31].

In
summary, favorable personality characteristics have been associated with
positive health outcomes in late life and longevity through various mechanisms.
Less is known regarding whether genetically homogenous groups of centenarians
share particular personality characteristics. Practical constraints to
assessing the personality of centenarians (e.g., cognitive/sensory impairment)
have also raised the need for a brief measure of personality. Therefore, this
study developed a brief measure of personality characteristics in centenarians
namely, the Personality Outlook Profile Scale (POPS), through examining the
construct and internal consistency of the POPS (scale development study), as
well as the concurrent validity of the POPS with the NEO-FFI, and LOT-R
(validation study). To increase our ability to detect genetically-based
personality phenotypes, the study targeted a genetically homogeneous sample of
Ashkenazi Jewish centenarians.

RESULTS

Demographic
Characteristics of the Participants

Demographic,
cognitive, and personality characteristics of centenarians are presented in
Table 1. The participants in the scale development study (N = 243) had a mean
age of 97.6 ±2.79 and were predominantly female (75%). Years of education
ranged from 0 to 25 years with a mean level of 12.7±3.89 years. The MMSE mean
score was 19.8±11.95. The participants of the self-report group in the
validation study (n = 19) had a mean age of 99.8 ±2.87 and were predominantly
female (68%) with a mean score of 5.63±1.54 in the MIS-T, indicating that all
were cognitively intact. The participants in the informant-report group of
centenarians (n = 26) had a mean age of 100±2.27 and were predominantly female
(69%). The mean scores and standard deviations (SD) of personality measures in
the validation study, the population means of the NEO-FFI based on the
normative data (derived from a representative sample of the US population) [7],
and the mean score of the LOT-R based on a mixed age group (age 36 to 82 years
with a mean age of 64.3 years) [32] are also presented in the Table 1.
Centenarians in both self- and informant-report groups tended to be optimistic,
easygoing, and outgoing and to consider laughter as an important part of their
life, based on the raw mean scores of items on the POPS (ranging from 3.34 to
4.09 in the self-report group and from 3.68 to 4.21 in the informant-report
group on a scale of 1 through 5). Further, the results of t-tests to compare
mean scores of the NEO-FFI traits in the current sample to the normative
population mean scores [7] found that participants in the self-report group
showed lower mean scores of neuroticism, t[18] = -3.81, p < .01, as well as
higher mean scores of extraversion, t[18] = 3.03, p < .01, agreeableness,
t[18] = 3.82, p < .01, and conscientiousness, t[18] = 2.42, p < .05, than
the US population
means. Participants in the informant-group also showed lower mean scores of
neuroticism, t[25] = -.2.24, p < .05, and higher mean scores of
conscientiousness, t[25] = 2.88, p < .01, than the US population means. The
results of t-tests to compare the mean score of the LOT-R in the current sample
to the mean score of a mixed age group [32] also showed that participants in
the informant-report group had a higher mean score of dispositional optimism,
t[25] = 2.60, p < .05, than the mean score of the mixed age group.

Validation
Study: The Concurrent Validity of the POPS with Personality Measures

The validation study examined the
concurrent validity of the POPS with the NEO-FFI and LOT-R. The results of the
bivariate correlations (Tables 3) demonstrated that, in the self-report group
of centenarians, PATL was positively associated with extraversion (r = .82, p
< .01) and
conscientiousness (r = .53, p < .05). EE was also negatively correlated with
neuroticism (r = -.51, p < .05). In the informant report group of
centenarians, PATL was negatively correlated with neuroticism (r = -.52, p <
.01), and positively correlated with extraversion (r = .74, p < .01) and
dispositional optimism (r = .69, p < .01). Additionally, EE was positively
associated with extraversion (r = .45, p < .05). There were no other
significant associations between the POPS domains and other personality
traits/measures in both groups.

DISCUSSION

The purpose of the present study was to detect genetically-based personality phenotypes
through developing a brief
measure of personality of centenarians, the Personality Outlook Profile Scale
(POPS) and examining its construct, internal consistency (scale development study), and concurrent validity with the NEO-FFI and LOT-R (validation study) in a
sample of Ashkenazi Jewish centenarians. The scale development study generated two domains: domain 1, Positive Attitude Towards
Life (PATL: optimism, easygoing, laughter, and introversion/out-going); domain 2,
Emotional Expression (EE: expressing emotions openly and not bottling up
emotions). These domains evidenced adequate levels of internal consistency.
Findings of the validation study demonstrated moderate to high associations
between the POPS and select personality traits from the NEO-FFI and LOT-R.
Specifically, PATL was highly associated with extraversion in both groups. PATL
was also moderately associated with conscientiousness in the self-report group,
and moderately to highly associated with dispositional optimism and neuroticism
(negative correlation) in the informant-report group. EE was moderately and
negatively associated with neuroticism in the self-report group and was
moderately associated with extraversion in the informant-report group. There-fore,
findings suggest that the POPS has acceptable psychometric characteristics and
measures personality aspects of extraversion, neuroticism, and possibly
conscientiousness, as well as dispositional optimism.

Particularly noteworthy findings were the favorable personality
characteristics of centenarians in this study compared to the US population
means, and personality characteristics of centenarians found in this study seem
to be consistent with findings from previous studies. Specifically,
centenarians in both self- and informant-report groups in the validation study
showed lower mean scores of neuroticism and higher mean scores of
conscientiousness than the US population means. These results coincided with
several studies that have identified that centenarians may share higher levels
of extraversion and conscientiousness, and low levels of neuroticism [9,11].
However, whether centenarians have maintained these particular personality
traits across their lifespan remains unknown since this question has not been
addressed longitudinally, although some age-associated changes in personality
in older adults have been reported [7,33].

The present study has a number of limitations. Although the use of
a genetically and environmentally homogeneous sample was an effective method to
identify genetically-based personality phenotypes, the use of a homogeneous
group potentially reduces the generalizability of this study's findings.
However, because Ashkenazi Jewish individuals are not expected to have more
longevity than other groups and their survival/causes of death are similar to
those reported in the general Caucasian US population [34], we do not expect
that their personality phenotypes are unique, and thus our findings may well be
relevant to other populations. Another limitation of this study is that the
sample size of the validation study was small because most participants in the
original study were unable to participate due to their health issues or
mortality. There were some methodological challenges in assessing centenarians'
personality characteristics using the self-report measures include their
sensory impairment, cognitive constraints, and physical disabilities. In the
scale development study, the Centenarian Questionnaire was completed by
participants with the assistance of a family member in order to increase the
reliability of participants' responses to the questionnaire. Also, in the
validation study, the informant-report group was used in addition to the
self-report group. Although sufficient levels of the agreement between self-
and informant-reports on personality measures have been demonstrated [35,36],
informant-reports may not represent the true personality characteristics of the
participants.

In summary, the findings of the present study demonstrated that
the POPS displays adequate psychometric characteristics as a brief measure of
personality in centenarians and measures aspects of neuroticism, extraversion,
and possibly conscientiousness, as well as optimism. This study adds to a
growing body of knowledge which suggests that centenarians may share particular
personality characteristics and suggests that genetically-based aspects of
personality may play an important role in achieving positive health outcomes
and exceptional longevity. Future research should continue to examine further
reliability and validity (e.g., discriminant validity) of the POPS as the
development of brief and robust measures of personality, validated for the
oldest old, in order to stimulate further research regarding successful aging
in this rapidly growing population.

METHODS

Participants

As part of the Longevity Genes Project,
Ashkenazi Jewish centenarians (age 95 to 107), who were living independently at
95 years of age as a reflection of good health, were recruited [34]. The use of
the Ashkenazi Jews in this study was due to their genetic and environmental
homogeneity which is an effective method to facilitate genetic association.
Survival and causes of death in the Ashkenazi Jewish population are similar to
those reported in the general Caucasian US population, and participants also had
relatively similar socio-cultural, economical, and educational back-grounds.
The study's sampling, recruitment, and procedures have been described
previously [34,37-39]. Within the archival data consisting of N = 396
Ashkenazi Jewish centenarians (age 95 to 107), 153 individuals were excluded
due to missing questionnaire responses. These individuals were not different
from the participants who were included in the analysis. Thus, N=243
participants were included in the scale development study. For the validation
study, cognitive screening measures were employed to reduce variance due to
cognitive impairment. N=210 cognitively intact centenarians, who scored 24
points or higher on the Mini-Mental State Exam (MMSE) were selected. Of those,
102 subjects were still alive at the time of this study, and 26 centenarians
and their children were available to participate. Most were unable to
participate in the study due to their health issues and practical constraints.
Of these, 7 centenarians in the self-report group were excluded due to health
issues and cognitive impairment (scores of lower than four points on the Memory
Impairment Screen by Telephone) [40]. Therefore, participants in the validation
study included centenarians (n=19) in the self-report group and their children
(n=26) in the informant-report group.

Procedures

In
the Longevity Genes Project, the Centenarian Questionnaire was filled out by
participants with the assistance of their children in the event that
participants had difficulty responding to questions in a reliable manner (e.g.,
due to mild cognitive and sensory/motor impairment). A single research nurse
administered the MMSE to each participant. In the validation study, MIS-T [40],
POPS, NEO-FFI [7], and LOT-R [32] were administered to centenarians through an
in-person or phone interview (self-reports). Their children were also asked to
complete the personality measures through an in-person or phone interview or by
mail (informant-reports).

Measures

The
98-item Centenarian Questionnaire, developed by the Longevity Genes Project,
measures participants' personal demographics, personality, health/medical history,
and health-related behaviors [41]. This questionnaire had served as the basis
for the development of the POPS. Initially, 11 items of the Centenarian
Questionnaire, which reflected centenarians' lifetime personality and related
behaviors, were selected as candidate items for the POPS. These items were
developed using a rational content-based approach and derived from extant
longevity research and theoretical concepts. Based on a principal component
analysis, six of the original eleven candidate items were selected, and two
robust components were identified: Positive Attitude Towards Life (PATL:
optimism, easygoing, laughter, and introversion/outgoing) and Emotional
Expression (EE: expressing emotions openly and not bottling up emotions). A
composite score of each domain is based on a mean z-score of respective
personality items for each domain. Higher scores reflect more favorable
personality traits.

NEO-Five Factor Inventory (NEO-FFI)

The
NEO-Five Factor Inventory (NEO-FFI) is a self- and informant-report 60-item
inventory which is a short-version of the NEO-PI and measures five broad
dimensions of personality traits. Each personality trait scale is comprised of
12 likert-type items rated on a five-point scale. Total scale scores are
derived by summing responses of the 12 items for each trait. Higher scores
indicate higher levels on a given trait. The NEO-FFI has demonstrated
correlations with the NEO-PI ranging from .75 to .91 [7].

The Life Orientation Test-Revised

The
Life Orientation Test-Revised (LOT-R) is a measure of dispositional optimism,
which examines generalized expectancies about future life events. Likert-type
items are rated on a 0 (disagree strongly) to 4 point scale (agree strongly).
Total scores are derived by the summation of scores on six items; 4 items are
filler items and not scored. Scores range from 0 to 24, with 24 reflecting
extreme optimism, with a mean score of 15 in a mixed-age adult sample. The
LOT-R has adequate levels of internal consistency, test-retest reliability, convergent/discriminant
validity, and validity for older adults [32].

Mini Mental Status Exam (MMSE)

The
Mini Mental Status Exam (MMSE) is a standard 30-item measure validated as a
screening tool for cognitive impairment. The MMSE has demonstrated acceptable
levels of internal consistency, test-retest reliability, and concurrent
validity. A standard cutoff score of ≥24 on the MMSE26 for intact
cognitive function was required for inclusion in the validation study [42,43].

The Memory Impairment Screen by Telephone (MIS-T)

The
MIS-T is a telephonically administered adaptation of the Memory Impairment
Screen (MIS), a four-item screening test for dementia which assesses an
individual's verbal memory based on the delayed free and cued recall trials.
The MIS-T is a valid screening tool for Alzheimer's type dementia in older
adults. Total scores are derived by the summation of the correct responses. A
cut-off score of four has adequate levels of sensitivity (.80) and specificity
(.96) to detect Alzheimer's dementia [40,44], and a score of four or above was
required for inclusion in the validation study.

Statistical Methods

Analyses
were completed with the statistical software, SPSS Statistics (Version 17.0).
In the scale development study, a principal component analysis was conducted to
generate the domains of the POPS. Cronbach's alpha was computed to test the
internal consistency of each domain. In the validation study, the concurrent
validity of the POPS with other measures was examined using Pearson's
correlation coefficients.

ACKNOWLEDGMENTS

We thank many centenarians and their
families for their dedication and contribution to this study. We also thank Mr.
William Greiner, the research nurse and other members of the Longevity Genes
Project for their contributions and support. This research was supported in
part by the National Institute of Aging, Grant P01 (AG027734; AG028872) and a
Nathan Shock Center grant.

CONFLICT OF INTERESTS STATEMENT

The authors of this manuscript have no conflict of
interest to declare.

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